The Consoles and their CPUs

The CPUs at the heart of these two consoles are very different in architecture approach, despite sharing some common parts.  The Xbox 360’s CPU, codenamed Xenon, takes a general purpose approach to microprocessor design and implements three general purpose PowerPC cores, meaning they can execute any type of code and will do it relatively well.

The PlayStation 3’s CPU, the Cell processor, pairs a general purpose PowerPC Processing Element (PPE, very similar to one core from Xenon) with 7 working Synergistic Processing Elements (SPEs) that are more specialized hardware designed to execute certain types of code. 

So the comparison between Xenon and Cell really boils down to a comparison between a general purpose microprocessor, and a hybrid of general purpose and specialized hardware. 

Despite what many have said, there is support for Sony’s approach with Cell.  We have discussed, in great detail, the architecture of the Cell processor already but there is industry support for a general purpose + specialized hardware CPU design.  Take note of the following slide from Intel’s Platform 2015 vision for their CPUs by the year 2015:

 

The use of one or two large general purpose cores combined with specialized hardware and multiple other smaller cores is in Intel’s roadmap for the future, despite their harsh criticism of the Cell processor.  The difference is that Cell appears to be far too early for its time.  By 2015 CPUs may be manufactured on as small as a 32nm process, significantly smaller than today’s 90nm process, meaning that a lot more hardware can be packed into the same amount of space.  In going with a very forward-looking design, the Cell processor architects inevitably had to make sacrifices to deal with the fact that the chip they wanted to design is years ahead of its time for use in general computation.

Index Introducing the Xbox 360’s Xenon CPU
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  • LanceVance - Friday, June 24, 2005 - link

    Excellent article. Definitely the most thorough, informative, well researched article on the PS3/Xbox360.

    And most importantly, unlike every other article on the subject, it's not strongly biased toward one camp while making comments of substance.
  • yacoub - Friday, June 24, 2005 - link

    I bet the PS3 debuts at a higher price.

    Also regarding statements made on the Conclusionary page:

    --"That being said, it won’t be impossible to get the same level of performance out of the PS3, it will just take more work. In fact, specialized hardware can be significantly faster than general purpose hardware at certain tasks, giving the PS3 the potential to outperform the Xbox 360 in CPU tasks. It has yet to be seen how much work is required to truly exploit that potential however, and it will definitely be a while before we can truly answer that question."--

    I find it funny that once again the PlayStation will be the harder system to code games for that take full advantage of its abilities. If trends mimic the past (as they often do) this will lead to a large amount of mediocre games by companies too small to afford the dev time necessary to take real advantage of the PS3's advantages or on deadlines too tight to spend the time doing more.
  • Furen - Friday, June 24, 2005 - link

    It does sound pretty low but (I'm guessing) it's more than enough, I dont think they would have separated the dies unless it didnt lead to a big performance penalty. also, I'm guessing that the 256MB/sec bandwidth between the eDRAM and its processing hardware is 256GB/sec? Microsoft was using that number to inflate their "system bandwidth" total.
  • Woodchuck2000 - Friday, June 24, 2005 - link

    And for that matter, 32Mb/s inter-die communications in the Xenos GPU seems low to me
    :p
    Good article though guys!
  • Furen - Friday, June 24, 2005 - link

    Is there any word on the media center extender capabilities on the xbox 360? I think Microsoft mentioned something about that but I'm not sure if that was oficial or not. Just hope they allow us to plug in some video capture device and use it as a dvr eventually.

    As much as I like sony's playstation, I find it quite boring on the technical side. It seems like they're just throwing everything they can into it but nothing is really that exciting, or useful. Come on, dual-HDMI. I dont see myself having two HDTVs in such close proximity to each other. Gigabit router? Seems like they're desperate to use the extra cpu muscle. I wonder how heavy ethernet traffic will affect cpu usage.
  • Woodchuck2000 - Friday, June 24, 2005 - link

    Surely porting between multi-core PC software and Xenon should be fairly trivial, not fairly Non-trivial as stated in the article...?
  • jotch - Friday, June 24, 2005 - link

    I stands for interlaced whilst the P stands for progressive scan. Check out the difference at http://en.wikipedia.org/wiki/720p

    or

    http://en.wikipedia.org/wiki/1080i

    This should resolve this issue.
  • AnnihilatorX - Friday, June 24, 2005 - link

    1080i = 720p doesn't it? 1080p is the one Xbox 360 doesn't support.

    These "i"s and "p"s are confusing me
  • sprockkets - Friday, June 24, 2005 - link

    How is 1080i on your tv's? On my 1 year old Mitsubishi native 1080i tv using dvi from the computer at 1080i is basically useless since the text is too small and the image looks like the refresh rate is below 60hz, whereas HDTV broadcasts look fine. Using the other mode of 720x480 looked great.

    Will HD output from a console be any better than a video card in a computer? Is it just my tv?

    Cmon, did you really think nVidia would release something far more advanced for a console than for a video card, or perhaps, more specifically, having it way outperform 6800 ultras in sli?

    If you need around a 400w power supply for even non sli setup, what kind of heat and power will these new consoles need anyhow???

    Of course I am more interested in how the PS3 will work with Linux more than games hahahahaha, since Sony officially mentioned it.
  • emmap - Sunday, December 4, 2005 - link

    And that's this article, Sony and M$ have missed:

    it's not the number of megapixels, shader pipelines, CPU / GPU bandwidth, multithreaded or single threaded code which do a great game. It's imagination put in the game, gameplay, artistic art quality, human feeling we get looking at the characters, fun and so on. It's not only mathematics and physics: we don't love a game because it has X millions polygons or run at Y fps, no it's totally different. Just see all the mame fans out there, you'll see that they don't care about the obsolete hardware the game they are playing on, they care about the most important thing about game: ENTERTAINMENT!

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